The relation of the flora of the New Jersey Pine Barrens to the 
geological history of the region* 
Raymond H. Torrey 
The relation of the peculiar flora of the Pine Barren region 
of southern New Jersey to the geological formations of the re- 
gion, and to the history of their origin and various modifications 
by submergence and erosion, has long been a subject of interest 
to botanists, ecologists and geologists. Some correlation between 
the remarkable and unusual plants found in the Pine Barrens 
within rather well defined limits, and the nature of the surface 
formations has been sought and a number of interpretations 
have been offered. The matter is still unsettled and a subject for 
amicable debate, but some of the probabilities which have been 
suggested by various authorities are here summarized. 
The source of the material which makes up hundreds of feet 
of sand, with some pebbly and clayey layers in the more arid 
portions of the Barrens, was unquestionably in the highlands in 
northern New Jersey and eastern Pennsylvania. These strata 
are composed mostly of detritus from ancient pre-Cambrian 
rocks, the principal minerals of which in the order of their fre- 
.quency, are quartz, feldspar, mica, magnetite, and hornblende. 
Detritus of all sizes was worn off these highlands, formerly much 
higher than now, and was carried by swift streams, probably fol- 
lowing more or less the same valley lines as are now followed by 
the Schuylkill, Lehigh, Delaware, Musconetcong, the upper 
waters of the Raritan, the Passaic and Hackensack Rivers. With 
interruptions due to repeated submergences of the continental 
shelf sometimes extending far back to the highlands, the general 
course of erosion was to carry off the waste of the uplands and 
lay it down in shallow water on the ocean front, from the Rari- 
tan Bay to Cape May. More than a thousand feet of material 
was thus laid down to make what is now south Jersey. The 
marl, or greensand formations along the western and northern 
borders of the Barrens were laid down in shallow water swarm- 
ing with marine life, at times cut off from the ocean, by the 
Sandy islands then existing between the Delaware and the ocean, 
in a broad inland strait something like Long Island Sound of to- 
ay. 
* Prepared for the week end field trip of the club on Sept. 25-27. 
169 
